Automotive drive



NOV. 19, 1940. W, g ms 2,222,144

AUTOMOTIVE DRIVE Filed April 10, 1959 4 Sheets-Sheet l WALTER FERRIS T: .nmfl mm A TORNEY.

Nov. 19, 1940. w. FERRIS 2,222,144

AUTOMOTI VE DRIVE Filed April 10, 1939 4 Sheets-Sheet 2 INVENTOR. "WALTER FEHHIS AT ORNEY.

Nov. 19, 1940. w. FEfQRIS AUTOMOTIVE DRIVE Filed April 10, 1959 4 Sheets-Sheet 3 INVENTOR.

U E R F E RR I s 'ATTZRNEY.

W. FERRIS AUTOMOTIV Nov. 19, 1940.

E DRIVE Filed April 10, 1939 4 Sheets-Sheet 4 INVENTOR. WALT EH F EFeFus rllfltllal ill; I

V Patented Nov. 19, 1940 UNITED STATES PATENT OFFICE AUTQMUTIVEE DEN/1E Walter Ferris, Milwaukee, Wis.-, assignor to The (lilgear Company, Milwaukee, Wis, a corporation of Wisconsin Application April 10, 1939, Serial No. 267,191 12 Claims. (01. i l-489.5)

This invention relates to drives of the type predetermined ratio to the speed of the prime which enables a prime mover to rotate a driven mover. member at variable speeds, and it is particu- Other objects and advantages will appear in larly adapted for transmitting motion from the the following description of the drive shown engine of an automotive vehicle to the driving schematically in accompanying drawings in 5 wheels thereof. For the purpose of illustration, which the views are as follows:

the invention will be explained as applied to an F 1 is a d a at c w S ow g a drive automotive vehicle, such as a truck or passenger in which the invention is embodied. bus, but it is to be understood that the invention Fig. 2 is a section l View taken on the line 2-2 is not limited to such use. of Fig. 1 and showing a pump which may be em- 1 Automotive vehicles are ordinarily provided p y as a part of the hydr ic transmission, with a mechanical transmission comprising a plue pp p Of the View being a transverse rality of gear trains of different ratios which t on ta thleugh e e ter Of the rotor and may be selectively engaged to enable the vehicle the lower p being e Section taken along the engine to drive the rear wheels at different speeds face of the rotor. 15 relative to the engine speed and which may be 3 is a w ShOWiIlg a yp s V e in a disengaged to permit the engine to run without p i i n ff r n fr m th h wn in Fi 1. driving the wheels. Such a transmission is ordi- Fig. 4.- is a section taken on line 4-4 of Fig. 1

narily connected to the engine through a clutch b dr wn to a l r scale nd showi a ifferat which may be disengaged to permit the gears to entiel wh h f rm a Part of a control mechabe shifted and thereby vary the speed of the n sm. wheels relative to the speed of the engine, the Fig. 5 is a detail view showing a friction disk speed ratio being varied in definite steps as detransmission which has one disk thereof contermined by the rati f the gears, nected to one leg of the differential shown in In order to obtain a stepless variation in speed 25 ratios, it has heretofore been proposed to re- FigS- 6 and 7 e Views Showing different pos place the mechanical transmission of an autotiOTlS Of a pilot Valve Which controls p p (11S- motive vehicle with a hydraulic transmission conpl n n i Operated y h difier ntial sisting primarily of a pump to be driven by the Shown in engine d a motor t be energized by t pump Figs. 8 and 9 are views showing different posiand drive the wheels However in order to trans tions of a control valve which controls the operamit enough power from the engine to the wheels tion of the p at s ShQWn in 10 e under extreme load conditions, a hydraulic trans- 3 5 10 and 11 F news showing dlfiere nt mission would necessarily be so large and heavy p0s 1t1nS of the plstons of a hydraulic devlce that Such an arrangement would not Ordinarily which is adapted to control the mechanical trans- 35 be practical. iSsion.

The present invention has as an Object to Fig. 12 is an elevation of a control lever for vide a drive which includes a mechanical transadjusting the friction disk transmission ShOwn mission for transmitting power from a prime in Fig. 5 and for controlling the solenoids which mover to a Shaft a hydraulic transmission ab operate the control valve shown in Figs. 8 and 9, 4,0

. the lever being shown in its neutral position.

ranged in parallel with the mechanical transmis- F1 g 13 is a View similar to the upper part of Sum and Including driven by the pnme Fig. 12 but with the control lever in an operative moverand a motor energized by the pump and position 4 connected Shaft to drlve h same and Fig. 14 is a vertical section through the conmeans slmultaneously rendermg 9 trol lever as indicated by line 14-44 on Fig. 12. transmission effective and the other transmission Fig. 15 is a view showing the lower part of the mefiectlve to transmlt power from the Prime control lever as viewed from the side opposite mover to e e that shown in Fig. 12 and as indicated by the Another obJect is to provide a drive of the above line 55.4 5 on Fig 4 5 character with means responsive to a variation For the purpose of illustration, the invention in th reIetive p s of the prime mover and has been shown embodied in a drive for an autothe shaft for varyin e relative d splacemotive vehicle of which, since it forms no part merits of the pump and the motor to thereby cause of the present invention, all parts have been the motor to drive the shaft at a speed having a omitted from the drawings except a part of the 55 engine I which drives the vehicle and a part of the propeller shaft 2 through which motion is transmitted in the usual manner to and from the rear wheels through the usual differential not shown.

Engine I is adapted to drive shaft 2 either through a mechanical transmission, which is arranged in a casing 3 carried by the frame of a vehicle, or through a hydraulic transmission which consists primarily of a variable displacement pump 4 and a hydraulic motor 5.

While pump 4 and motor 5 may be of any suitable type, they have been shown as being of the vane type for the reason that it is desirable that each be small and light relative to its volumetric capacity and that the shafts thereof, the main shafts of the mechanical transmission, the shaft of engine I and propeller shaft 2 be arranged in axial alinement. A pump which may be employed is fully illustrated and described in Patent No. 2,141,170. Consequently, pump 4 has not been illustrated in detail and only a brief description thereof will be given herein.

Referring now more particularly to Fig. 2, pump 4 has a plurality of vanes 6 closely fitted in suitable slots which are formed in a rotor I and extend approximately radially inward from the periphery thereof.

Rotor I is fixed for rotation with a shaft 8 and closely fitted between two end plates 9 which are spaced apart by two approximately semi-circular spacer plates I0 and arranged therewith in a casing II. Only one of the end plates 9 has been shown and that plate is provided with two diametrically opposed ports I2 and two diametrically opposed ports I3 which, when rotor I is rotated in the direction indicated by the arrow, function as discharge and intake ports respectively. Ports I2 and I3 are connected, respectively, through passages (not shown) to an outlet channel I4 and an intake channel I5 by means of which pump 4 is connected into an external circuit.

Each spacer plate I0 is provided with a bridge I6 which has an arcuate inner face arranged in close proximity with the periphery of rotor I. The two bridges I6 are arranged diametrically opposite each other and divide the space between the periphery of rotor I and the inner peripherical surface of spacer plates I0 into two compartments each of which is divided into a discharge chamber I1 and a suction chamber I8 by the vanes engaging the arcuate inner face of an adjustable bridge I9 which is fitted between end plates 9 and between the adjacent ends of spacer plates I8 and forms a fluid tight joint therewith. Each discharge chamber I'I communicates with a discharge port I2, and each suction chamber I8 communicates with an intake port I3.

The two bridges I9 are arranged diametrically opposite each other and each is provided upon each of its upper and lower sides with a vane track section 28 which has one end thereof fixed to bridge I9 and its other end arranged in a slot formed in an end of the adjacent bridge I6, a projection 2| on the free end of each track section engaging the inner surface of spacer plate In to hold the inner face of the track section flush with the inner face of bridge I6. The four track sections 20 and the inner faces of bridges I6 and I 9 form a continuous track upon which the outer ends of vanes 6 ride as rotor I rotates.

The arrangement is such that, when the inner faces of bridges I6 and I9 are equally spaced from the periphery of rotor 1, pump displacement is zero and no liquid will be discharged but, when bridges I9 are moved outward and rotor I is rotating in the direction indicated by the arrow, vanes 6 will transfer liquid from suction chambers I8 to discharge chambers I1 and thereby cause the pump to draw liquid through intake channel I5 and discharge it into outlet channel I4 at a rate determined by the speed of rotor I and. the distance the inner faces of bridges I9 are spaced from rotor I in excess of the distance the inner faces of bridges I6 are spaced from rotor I. Consequently, the displacement of the pump may be varied by moving bridges I9 inward or outward.

As shown, each bridge I9 has fixed thereto a rod 22 which extends outward through the wall of casing II and is provided on its outer part with a collar 23 for stopping its inward movement when bridge I9 reaches its zero displacement position.

Each rod 22 is connected at its outer end by means of a pin and slot connection to the lower end of a lever 24 which is pivoted intermediate its ends upon a bracket 25 carried by casing I I. The upper end of each lever 24 is connected by a link 28 to a crosshead 2! fixed upon the rod 28 of a piston 29 which is fitted in a cylinder 30 carried by casing II.

The arrangement is such that, when liquid is supplied to the upper end of cylinder 38, piston 29 will move downward and cause bridges I9 to move inward to reduce pump displacement and, when liquid is supplied to the lower end of cylinder 30, piston 29 will move upward and cause bridges I9 to move outward to increase pump displacement.

Liquid for operating piston 29 is preferably supplied from a source which is independent of the liquid discharged by pump 4, such as a gear pump 35 (Fig. 1) which is attached to pump casing II and supplied with liquid from a reservoir 36 which has been shown attached to the lower part of pump casing I I.

Gear pump 35 hasone of its gears fixed upon shaft 8 which is connected in any suitable manner to the shaft 3'! of engine I so that pumps 4 and 35 are driven continuously when engine I is running, and pump 35 will deliver liquid regardless of whether or not pump 4 is delivering liquid.

Gear pump 35 draws liquid from reservoir 36 through a channel not shown and discharges it into a supply channel 38 one branch of which is connected to the upper end of cylinder 30 so that the upper face of piston 29 is continuously subjected to gear pump pressure as long as engine I continues to run. The delivery of gear pump liquid to the lower end of cylinder 30 and the operation of piston 29 is controlled by a speed responsive mechanism to be presently described.

Motor 5, which is arranged within and supported by a casing 39 connected to transmission casing 3 and supported by the frame of the vehicle, may be of a vane type similar to pump 4 but without adjustment to vary its displacement. Consequently, it is deemed sufficient to state herein that it is provided with a shaft 8* which corresponds to shaft 8 of pump 4 and which is connected at its rear end to propeller shaft 2 by any suitable means such as a universal joint 40, that shaft 8 will be rotated when motor 5 is supplied with liquid from pump 4, that the direction of rotation may be reversed by reversing the flow of liquid, and that liquid for energizing motor 5 is supplied thereto through one or the other of two channels 4| and 42 which are connected to the two ports of motor 5.

In order to reverse the flow of liquid, channels !4, I5, 4| and 42 are connected to a valve casing 44 having fitted therein a reversing valve 44 which has been diagrammatically shown as a rotary valve but which is preferably of the plunger type.

Valve 44 has been shown as having a pinion 45 fixed upon its stem and in mesh with a. rack 46 which is urged in one direction by a spring 41 and adapted to be moved in the opposite direction by a solenoid 48, the movement of rack 46 in each direction being limited by suitable stops.

Solenoid 48 is controlled by a normally open switch 49 which has one of its terminals grounded, as by being connected to the frame of the vehicle, and its other terminal connected by a conductor 56 to one end of the winding of solenoid 48 the other end of which is connected by a conductor 5| to one terminal of a battery 52, the other terminal of battery 52 being grounded as by being connected to the frame of the vehicle.

The arrangement is such that, when valve 44 is in the position shown in Fig. 1, the liquid discharged by pump 4 will fiow through channel I4, valve casing 43 and channel 4| to motpr '5 and cause it to rotate shaft 8 in the direction of the arrow and thereby cause the vehicle to be driven in a forward direction at a speed proportional to the displacement of pump 4 and the liquid exhausted from motor 5 will flow through channel 42, valve casing 43 and channel I5 to the intake of pump 4.

When switch 49 is closed, solenoid 48 will shift valve 44 to the position shown in Fig. 3 and then the liquid discharged by pump 4 will flow through channel l4, valve casing 43 and channel 42 to motor 5 and cause it to rotate shaft 8 in the opposite direction and thereby cause the vehicle to be reversed, and the liquid exhausted from motor 5 will flow through channel 4|, valve casing 43 and channel to the intake of pump 4. When switch 49 is opened, spring 41 will shift valve 44 to the position shown in Fig. 1.

In order to prevent excessive pressures from being developed in either direction of motor actuation, two oppositely opening high pressure relief valves 53 and 54 are connected between opposite sides of the circuit as by being connected be tween channels 4| and 42.

Since a hydraulic transmission has a certain amount of leakage or slip, means are provided for supplying additional liquid to pump 4 to compensate for such slip. As shown, channel It: is connected to reservoir 36 through a check valve 55 which permits pump 4 to draw liquid from reservoir 36 but prevents liquid from escaping from channel l5 into reservoir 36.

The slip of a hydraulic transmission is substantially zero at zero pressure but increases as the pressure increases. Therefore, pump 4 must tend to deliver liquid to motor 5 at a rate which exceeds the requirements of motor 5 by an amount equal to the slip. When the mechanical transmission is rendered effective to drive shaft 2, the pressure in the hydraulic transmission will drop and thereby cause the slip to decrease with a resultant increase in the net delivery of pump 4 so that unless means are provided to render the hydraulic transmission ineffective to drive shaft 2 when the mechanical transmission is driving it, motor 5 would tend to drive shaft 2 at a speed in excess of the speed at which it is being driven by the mechanical transmission.

To this end, there is connected between the two sides of the hydraulic circuit, as by being connected between channels 4| and 42, a bypass valve 56 which is opened in response to the mechanical transmission being rendered effective and closed in response to the mechanical transmission being rendered ineffective as will presently be explained.

Bypass valve 56 may be large enough to bypass the entire discharge of pump 4 but, in order that the hydraulic transmission may function as a brake for decelerating the vehicle as will presently be explained, 5 6 is p referably only large enough" to bypass"l'iquid at a rate which .1011}; sli ht i .ezi ee iihe r e .slii f l m The mechanical transmission ordinarily has at least three speeds forward and one reverse, and these four speeds are selected by shifting a lever in opposite directions in two different planes. Since such transmissions are well known and in extensive use, the transmission has been shown schematically and the gears for obtaining two of the speeds have been omitted from the drawings in order to avoid complicating the View.

As shown, the mechanical transmission is provided with two shafts 60 and 6| which are journaled in transmission casing 3 in axial alignment with each other and with pump shaft 8 and motor shaft 8 Shaft 6| is connected at its rear end to the front end of motor shaft 3 while shaft 66 is adapted to be driven by engine I through a friction clutch consisting primarily of a disk 62, which is fixed upon the rear end of pump shaft 8, and a disk 63 which is splined upon shaft 60 and urged against disk 6| by a spring 64.

Shafts 60 and 6| are adapted to be connected to each other by a jaw clutch consisting of a clutch member 65, which is fixed upon shaft 68, and a clutch member 66 which is fixed upon a sleeve 61 splined upon shaft 6|.

Sleeve 6'! also has a gear 68 fixed thereon and adapted to be moved into mesh with a gear 69 fixed upon a countershaft 10 which is arranged parallel to shafts 66 and 6| and journaled in the walls of casing 3. Shaft 76 has a gear 1| fixed thereon and constantly in mesh with a gear 12.

which is fixed upon shaft 66.

Since pump shaft 8 is permanently connected to engine shaft 31, pump 4 will be driven and shaft 8 rotated whenever engine is running.

When pump 4 is adjusted to deliver liquid and sleeve 61 is in the position shown, at which time bypass valve 56 is closed and clutch 6566 is disengaged, the liquid discharged by pump 4 will energize motor 5 and cause it to drive propeller shaft 2. engaged, at which time bypass valve 56 is open so that the hydraulic drive is ineffective, propeller shaft 2 will be driven through the mechanical transmission at a speed equal to the speed of engine When clutch 62-63 is engaged and gears 68 and 69 are in mesh, at which time bypass valve 56 is open so that the hydraulic transmission is ineffective, propeller shaft 2 will be driven through the mechanical transmission at a speed having a ratio to the engine speed determined by the ratios of gear H and 12 and gears 68 and 69. Consequently, when one transmission is rendered effective to drive propeller shaft 2, the other transmission is automatically rendered ineffective.

When clutches 6263, and 65-66 are.

Clutch 6263 is adapted to be disengaged by a lever I5 which is pivoted intermediate its ends upon a stationary pivot 16 and has its upper end provided with a foot pedal 11 and its lower end bifurcated and arranged between suitable shoulders formed upon the hub of disk 63.

Sleeve 61 is adapted to be shifted along shaft 6|, to engage or disengage clutch 65--66 and to move gear 68 into or out of mesh with gear 69, by a lever I8 which is pivoted intermediate its ends upon a stationary pivot I9 and has its upper end provided with a handle 80 and its lower end bifurcated and arranged between suitable shoulders formed upon sleeve 61.

In order that bypass valve 56 may be operated in response to movement of sleeve 61 along shaft 6I, lever I8 has an arm 8I fixed thereto in alinement with pivot I9 and the outer end of arm BI is connected by a link 82 to a lever 83 which is fixed to the stem of bypass valve 56. The arrangement is such that, when lever I8 is operated to shift sleeve 61 to its neutral position as shown, arm 8| will cause link 82 and lever 83 to close bypass valve 56 and, when lever 18 is operated to shift sleeve 67 in one direction or the other to thereby cause clutch member 66 to engage clutch member 65 or to cause gear 68 to mesh with gear 69, arm M will cause link 82 and lever 83 to open bypass valve 56.

In order that clutch 6566 may be readily engaged or gear 68 readily meshed with gear 69 when the drive is in operation, motor 5 is adapted to have its speed regulated to thereby synchronize shaft 6| with shaft 60 or gear 66 with gear 69. This is accomplished by means of a control mechanism which adjusts the displacement of pump 4 to thereby regulate the speed of motor 5 in response to a variation in the relative speeds of pump 4 and motor 5.

40 As shown, the control mechanism includes a pilot valve 85 which controls the flow of motive liquid to and from pump control cylinder 30, a differential gear unit 86 which has one leg driven through a variable speed friction disk transmis- 45 sion 81 at a speed proportional to the speed of 55 placement of pump 4 and acts to close pilot valve 85 when the adjustment of pump displacement has resulted in correcting such departure from the preset ratio.

Pilot valve 85 has formed in its casing three annular grooves or ports 88, 89 and 90 communication between which is controlled by a valve member 9I which is closely fitted in the valve casing and so shaped that a slight move-- ment thereof in one direction or the other will open port 90 to one or the other of ports 88 and 89.

Port 88 and both ends of the valve casing are connected to a drain channel 92. Port 89 is connected through a channel 93 and a shut off valve 70 94 to gear pump supply channel 38 so that it is constantly supplied with motive liquid when engine I is running and valve 94 is in the position shown in Fig. 1. Port 90 is connected through a channel 95, a choke 96 and a channel 9! to the 75 lower end of cylinder 30.

Pilot valve member 9I has its stem connected to one end of a floating lever 98 which is connected intermediate its ends by a link 99 and a crank I00 to the third leg of differential 86 and has its other end connected to a follow-up mechanism which operates in response to adjustment of pump 4.

As shown, lever 98 is connected by a link IOI to one arm of a bell crank lever I02 which is pivoted upon a stationary pin I03. The other arm of lever I02 is connected by a link I04 to one arm of a bell crank lever I05 which is pivoted upon a stationary pin I06 and has its other arm connected by a link I01 to the rod of piston 29.

The arrangement is such that, when operation of differential 86 causes valve member 9I to be shifted downward and open port 90 to port 89 as shown in Fig. 7, liquid from gear pump 35 will flow through channel 38, valve 94, channel 93, pilot valve 85, channel 95, choke 96 and channel 91 to the lower end of cylinder 30. Since the lower face of piston 29 has a considerably greater effective pressure area than the upper face thereof due to the displacement of rod 20, the liquid entering the lower end of cylinder 30 will cause piston 29 to move upward and thereby increase the displacement of pump 4 as previously explained. When valve 9| is shifted upward to open port 90 to port 88 as shown in Fig. 6, liquid may escape from the lower end of cylinder 30 through channel 91, choke 96, channel 95 and pilot valve 85 into drain channel 92, thereby permitting liquid from gear pump 35 to flow through channel 38 to the upper end of cylinder 30 and move piston 29 downward to reduce the displacement of pump 4 as previously explained. Choke 96 will limit the rate at which liquid may flow to and from the lower end of cylinder 30 and thereby limit the rate at which the displacement of pump 4 is varied.

As soon as pilot valve member 9i starts to move in one direction, piston 29 will start to move in the opposite direction and will move link I0'I with it. Link I0'I will swing lever I05 upon pin I06 and cause link I04 to swing lever I02 upon pin I03 which will cause link IM to move in the same direction that valve member 9I moves, thereby tending to swing lever 98 upon link 99 so that the follow-up mechanism tends to close valve 85 as fast as differential 86 opens it. Consequently, valve 85 is closed as soon as the third leg of differential 86 ceases to rotate.

Differential 86 is provided with a case I I2 (Fig. 4) which has an internal gear II3 fixed therein and two hollow hubs H4 and H5 arranged upon opposite ends thereof and journaled in suitable bearings carried by casing 39. Hub H4 is connected by means of a suitable drive I I6 to motor shaft 8 so that difierential case 86 is driven in unison with motor 5 and propeller shaft 2.

A planet pinion II'I meshes with internal gear I I3 and is rotatably carried by a crank II8 fixed upon the inner end of a shaft II9 which is journaled in hub H5 and extends outward through the end thereof.

Planet pinion II! also meshes with a sun gear I20 fixed upon the inner end of a shaft i2I which is journaled in hub H4 and has crank I00 fixed upon the outer end thereof.

Differential case H2 and shaft II9 are adapted to be driven in the same direction, as indicated by the arrows on Fig. 1. When difierential case H2 and shaft II9 are driven at the same speed, shaft I2I will remain stationary and pilot valve I rotate.

member 6i will remain in its neutral position as shown in Fig. 1.

When the speed of differential case H2 is less than the speed of shaft H9, sun gear I26 and shaft I2I will be rotated in the same direction that case H2 is rotating, thereby causing lever I to be swung downward and lower pilot valve member 9i so that gear pump liquid may flow to the lower end of cylinder 36 and cause piston 29 to increase the displacement of pump 4 as previously explained. Pump 4 will then deliver liquid at an increased rate to increase the speed of motor until it is driving differential case H2 at a speed equal to the speed of shaft H9.

When the speed of case H2 is greater than the speed of shaft H9, sun gear I26 and shaft I2I will be rotated in a direction opposite to that in which case H2 is rotating, thereby causing lever IllO to swing upward and raise pilot valve member 9| so that liquid may escape from the lower end of cylinder 39 and cause piston 29 to decrease the displacement of pump 4 as previously explained. Pump 4 will then deliver liquid at a decreased rate and cause the speed of motor 5 to be decreased until it is driving differential case I I2 at a speed equal to the speed of shaft I I9.

As previously explained, shaft H9 is adapted to be driven through friction disk transmission 81. As best shown in Fig. 5, transmission 81 has a driven disk I fixed upon the outer end of shaft II 9, a driving disk I26 fixed upon a shaft I21 which is rotatably supported by the frame of the vehicle and connected by a suitable drive I28 to pump shaft 8 so that disk I26 is driven at a speed proportional to the speed of shaft 8, and a transfer disk I29 for transmitting motion from disk I26 to disk I25.

When transfer disk I29 engages driving disk I26 at the center thereof, it will not be rotated and motion will not be transmitted thereby to driven disk I25. When disk I29 is moved downward so that it engages disk I26 at a point spaced from the center thereof as shown in Fig. 5, it will be rotated by disk I26 and cause disk I25 to The speed of disk I25 relative to the speed of disk I26 is determined by the distance that disk I29 is spaced from the center of disk I26.

Transfer disk I29 has been shown as being fixed upon a shaft I 30 which is pivoted between suitable shoulders formed upon a slide I3l havin a rod I32 fixed thereto and fitted in a guide I33 carried b cas ng 39.

Slide I3I (Fig. 5) is connected by link I34 to an arm I35 (F gs. 1 and 12) forming a part of control lever I36 which is provided at its upper end with a handle I31 and is pivoted at its lower nd upon a bracket I33 carried by casing 39. It will be obv ous that movement of lever I36 in one direction or the other will cause transfer disk I29 to be raised or lowered and thereby vary the speed of disk I25 relative to the speed of disk I26.

In order that lever I36 may be retained in any position, bracket I38 is provided with a quadrant I39 consisting primarily of two spaced f apart side members having arcuate upper faces,

and lever I36 extends between the side members and is provided with a friction shoe I43 which is urged against the upper face of quadrant I39 by a spring I4I. Shoe I46 has a stem I42 formed thereon and fitted in two guides I43 and I44 carried by lever I36, and spring I4l encircles stem I42 between guide I43 and a suitable collar carried by stem I42.

In order that lever I36 may be retained in any one of a plurality of selective positions, it

is provided with a latch to engage any one of a plurality of notches formed in quadant I 39.

As shown, quadrant I39 has three notches I56, I5I and I52 formed therein and adapted to be engaged by a latch I53 which is slidable through two guides I54 and I55 carried by lever I36. Latch I53 is urged toward quadrant I39 by a spring I56 arranged between guide I54 and a suitable collar fixed upon latch I53.

Notches I56, I5I and I52 are so located that, when latch I53 is in notch I56, lever I36 will hold transfer disk I29 in contact with the center of disk I26 in which position of transfer disk I29 no motion is transmitted from shaft 8 to differential 86 so that the displacement of pump 4 will be zero and motor 5 will not be energized.

When lever I36 is advanced until latch I53 engages notch I5I, disk I29 will move downward as shown in Fig. 5 and enable disk I26 to drive disk I25 at the proper speed to cause the displacement of pump 4 to be so adjusted that it will deliver just sufficient liquid to cause motor 5 to rotate shafts 6 and 6| at such a speed ratio that the peripheral speed of gear 68 is equal to the peripheral speed of gear 69 so that gear 68 may readily mesh with gear 69.

When lever I36 is advanced until latch I53 engages notch I52, disk I29 will be moved farther from the center of disk I26 so that it is driven at a higher speed and drives disk I25 at the proper speed to cause the displacement of pump 4 to be so adjusted that it will deliver just sufficient liquid to cause motor 5 to synchronize shafts B and GI with shaft 66 so that clutch I55-66 may be readily engaged.

In order that latch I53 may be retracted out of contact with quadrant I39, a bell crank hand grip I51 is connected at its rear end by a pin I58 to lever I36 just below handle I31 and connected at the junction of its two arms by a link I59 to the upper end of latch I53 so that, when the operator grasps handle I31, he may draw the vertical arm of hand grip I51 toward handle I31 and thereby cause hand grip I51 to swing upon pin I58 and raise latch I53.

In order that latch I 53 may be held out of contact with quadrant I39, a spring catch I66 is arranged upon the end of handle I31 and adapted to lock the upper end of hand grip I51 when latch I53 is fully retracted, thereby preventing latch I53 from being moved downward by spring I56 when hand grip I51 is released by the operator. To release latch I53, the operator simply raises the end of latch I66 when he grasps handle I31 to shift lever I36.

When latch I53 is held out of contact with quadrant I39, lever I36 is held in any adjusted position by friction shoe I engaging the face of quadrant I39. The purpose of latch I53 is to positively fix lever I36 in such a position that disk I29 will either be in its neutral position or be in a position to either cause shaft 6I to be synchronized with shaft 66 or to synchronize gear 66 with gear 69 so that clutch 65-66 may be readily engaged or gear 68 readily meshed with gear 69 as previously explained.

Clutch 65-66 may be engaged and gear 68 may be meshed with gear 69 either automatically or by manual operation of gear shift lever 16. As shown in Fig. 1, lever 18 is pivoted intermediate its ends to a rod I6I intermediate the ends thereof. Rod I6I has one of its ends connected to a piston I 62 which is fitted in a stationary cylinder I63 and forms therewith a servo-motor for operating lever 18.

The other end portion of rod I6I has two collars I64 and I65 fixed thereon and two pistons I66 and I61 closely fitted to slide thereon between collars I64 and I65. Pistons I66 and I61 are closely fitted in the bore I68 of a stationary cylinder I69 and form therewith a servo-motor for moving lever 18 to its neutral position.

The effective pressure areas of pistons I66 and I61 are considerably smaller than the area of piston I62 so that, when liquid is delivered to cylinders I63 and I69 at the same pressure, servo-motor I62I63 is able to shift lever 18 against the resistance of servo-motor I66-I69.

The distance between the ends of bore I68 is the same as the distance between the adjacent faces of collars I64 and I65 and bore I68 is ordinarily supplied through channel 93 with gear pump liquid at all times so that, when servo-motor I62I63 is not energized, the pressure in bore I68 will move pistons I66 and I61 against the ends of bore I68 and one of the pistons will engage one of the collars on rod I6I and shift lever 18 to its neutral position.

Liquid for operating servo-motor I 62l 63 is supplied thereto under the control of a valve I18 which is fitted in the bore of a valve casing sill having three annular grooves or ports I12,I13 and I14 formed therein.

Port I12 is connected to gear pump supply channel 93 by a channel I15, port I13 is connected to one end of cylinder I63 by a channel I16, port I14 is connected to the other end of cylinder I63 by a channel I11, and the bore in cylinder I1I has both ends thereof connected to a drain channel I18 which discharges into reservoir 36 and is also connected to shut-off valve 94.

Valve I10 is urged toward its central or neutral position as shown in Fig. 1 by two caged springs I19 and I arranged, respectively, in two spring chambers I8I and I82 which are formed in or arranged upon opposite ends of valve casing I1I. Valve I10 is adapted to be shifted in one direction or the other by two solenoids I83 and I84 which are arranged at opposite ends of valve casing HI and have the cores thereof connected, respectively, to opposite ends of valve I10 by suitable stems which extend through spring chambers I8I and I82.

Solenoids I83 and I84 are controlled by switches carried by the control lever mechanism. As shown, solenoid I83 has one end of its winding connected by a conductor I85 to the ungrounded terminal of battery 52 and the other end of its winding connected by conductor I86 to a spring contact I81 (Fig. 15) carried by a quadrant I39. Solenoid I84 (Fig. 1) has one end of its winding connected by conductor I88 to the ungrounded terminal of battery 52 and the other end of its winding connected by conductor I89 to a spring contact I90 (Fig. 15) carried by quadrant I39.

Spring contacts I81 and I90 are insulated from quadrant I39 and are arranged upon opposite sides of a double spring contact I9I which is grounded to the frame of the vehicle. Contacts I81, I90 and I9I are arranged below the upper flange of quadrant I39 which has suitable openings formed therein to permit the passage therethrough of a bridging contact I92 which is slidab-le through a guide I93 carried by lever I36.

The several contacts are so located that, when latch I53 (Fig. 12) is in position to engage notch I5I, contact I92 will be in position to bridge contacts I81 and I9I and, when latch I53 is in position to engage notch I52, contact I 92 will be in position to bridge contacts I90 and I9 I.

When contact I92 bridges contacts I81 and I9I, a circuit will be established from battery 52 through conductor I85, the winding of solenoid I83, conductor I86, contacts I81, I92 and I9I and the vehicle frame to battery 52, thereby energizing solenoid I83 which will shift valve I10 t0 the position shown in Fig. 8 so that liquid from gear pump 35 may flow through channel 38, valve 99, channel I15, valve casing HI and channel I11 to the right end of cylinder I63 and, as shown in Fig. 10, cause piston I62 to shift lever 18 in a direction to move gear 68 into mesh with gear 69.

When contact I92 bridges contacts I90 and I9I, a circuit will be established from battery 52 through conductor I88, the winding of solenoid I84, conductor I89, contacts I90, I92 and I9! and the vehicle frame to battery 52, thereby energizing solenoid I84 which will shift valve I10 to the position shown in Fig. 9 so that liquid from gear pump 35 may flow through channel 38, valve 94, channel I15, valve casing HI and channel I16 .to the left end of cylinder I63 and, as shown in Fig. 11, cause piston I62 to shift lever 18 in a direction to move clutch member 66 into engagement with clutch member 65.

Bridging contact I92 (Figs. 14 and 15) is fixed upon the end of a rod I94 which extends upward through lever I38 and is provided at its upper end with a button I95 (Fig. 12) by means of which it may be depressed to move contact I 92 into engagement with the spring contacts.

Rod I94 is urged upward by a spring I96 which is arranged within handle I31 and engaging an abutment I91 formed upon rod I94 near the upper end thereof. Abutment I91 is engaged by a leaf spring I98 which is fixed to handle I31 and adapted, when button I95 is fully depressed, to move abutment I91 toward the front of handle I31 and cause its upper end to catch beneath the upper end of handle I31 as shown in Fig. 13, thereby holding contact I92 in engagement with the spring contacts.

In order that bridging contact I92 may be retracted before lever I 36 can be shifted, hand grip I51 is provided near its upper end with a lug I99 which engages abutment I91 and moves it out of engagement with the upper wall of handle I31 when hand grip I51 is operated to withdraw latch I53 from one of the notches in quadrant I39.

Operation Assuming that the several parts are in the positions shown in Fig. 1, that the vehicle is stationary, that the displacement of pump 4 is zero and that engine I is running, the drive will operate as follows:

Shafts 8, 60, 10 and I21 will be rotated and pumps 4 and 35 will be driven by engine I. Neither shaft 60 nor shaft 10 can transmit motion to shaft 6| as clutch 6566 is disengaged and gear 68 is out of mesh with gear 69. Shaft I21 cannot transmit motion to differential 86 as disk I29 is in contact with disk I26 at the center thereof. Pump 4 cannot energize motor 5 as its displacement is zero. Pump 35 will discharge through its relief valve 200 which will enable it to maintain a predetermined pressure in channels 38 and 93 and cause servo-motor I64I69 to hold gear shift lever 18 in its neutral position.

If the operator wishes to use only the mechanical transmission, he turns the handle of valve 94 through 90 to connect channels 38 and 93 to drain channel I18, thereby by-passing pump 95 and connecting servo-motor ISL-I69 to drain so that lever I9 may be readily shifted to employ the mechanical transmission in the usual manner, clutch 62-433 being disengaged when gears are to be meshed or when clutch 65-456 is to be engaged.

If the hydraulic transmission is to be used, valve 99 is adjusted as shown. To start the machine, the operator advances control lever I96 from its neutral position, thereby moving disk I29 below the center of disk I26. Since disk I29 is rotating, it will cause disk I29 to rotate disk I and, since differential case H2 is stationary, rotating disk I25 will cause pilot valve member 9I to move downward and direct liquid to the lower end of control cylinder 39, thereby causing piston 29 to increase the displacement of pump 4 from zero so that pump 4 will start to deliver liquid to motor 5 which will start to rotate propeller shaft 2 and differential case H2 all as previously explained.

Rotation of differential case H2 will tend to move pilot valve member 9| to its neutral position but the displacement of pump 4 will continue to increase until motor 5 is driving shaft 2 at a speed which is determined relative to the speed of engine I by the distance that disk I29 is offset from the center of disk I26 at which time the speed of diiferential case II2 will equal the speed of disk I25 and pilot valve member 9| will be in its neutral position so that further adjustment of pump 4 will cease.

When the speed of shaft 2 varies relative to the speed of engine I due either to the speed of engine I being varied or to a variation in the load on shaft 2, disk I25 and differential case I26 will rotate at different speeds and thereby cause pilot valve member 9| to be shifted and direct liquid to or from the lower end of cylinder 30 so that piston 29 will vary the displacement of pump I until motor 5 is driving propeller shaft 2 at the speed determined by the speed of engine I and the position of disk I29.

The speed of shaft 2 relative to the speed of engine I may be steplessly varied between zero and full speed by simply shifting control lever 99 so that the vehicle may be readily started and easily handled in traflic.

When the operator has shifted lever I36 until latch I53 (Fig. 12) is in alinement with notch I5I or notch I52, he may raise catch I60 to release hand grip I5'I and permit spring I56 to advance latch I59 into the notch with which it is in alinement. After waiting an instant to give the speed control mechanism time to cause clutch member 95 to synchronize with clutch member 66 or gear 99 to synchronize with gear 69 as previously explained, he may depress button I95.

If latch I59 is in alinement with notch I5l, depressing button I95 will cause contact I92 to bridge contacts I8! and NH and establish a circuit through solenoid I93 which will then shift valve M9 to the position shown in Fig. 8 so that gear pump liquid may flow to the right end of cylinder I63 and cause piston I62 to shift lever IS in a direction to mesh gear 68 with gear 69.

If latch I59 is in alinement with notch I52, depressing button I95 will cause contact I92 to bridge contacts I99 and I9I and establish a circuit through solenoid I94 which will then shift valve M9 to the position shown in Fig. 9 so that gear pump liquid may flow to the left end of cylinder I63 and cause piston I62 to shift lever I9 in a direction to engage clutch member 66 with clutch member 65.

Shifting lever I8 causes by-pass valve 56 to open and by-pass at least a part of the liquid discharged by pump 9 so that, as soon as clutch 65-96 is engaged or gear 69 is in mesh with gear 69, the hydraulic transmission is rendered inefiective and the vehicle is driven solely through the mechanical transmission.

If the operator wishes to change to a different gear ratio or to control the vehicle hydraulically, he presses hand grip I5? toward handle I3! to raise latch I 59 out of engagement with quadrant I39. Lug I99 on hand grip I5I will move abutment I9I from underneath the top wall of handle I 3! and permit spring I96 to retract the bridging contact from between the spring contacts so that solenoid I83 or I94 is deenergized and permits valve III) to return to its neutral position and open both ends of cylinder I63 to drain so that servo-motor M l-J69 can shift lever I9 to put the mechanical transmission in neutral. The vehicle is then being driven through the hydraulic transmission which may be adjusted as explained above.

Since bypass valve 56 is opened when lever 18 is operated to connect shaft (M to shaft 69 either direptly or through intermediate gears and since valve 56 is closed when lever I3 is operated to disconnect shaft BI from shaft 69, engine I is always connected to propeller shaft 2 through one or the other of the two transmissions but never through both.

The invention herein set forth is susceptible of various modifications and adaptations without departing from the scope thereof as hereafter claimed.

The invention is hereby claimed as follows:

1. The combination, with a shaft and an engine for driving said shaft, of a mechanical transmission having one part thereof connected to said shaft to drive the same and another part connected to and driven by said engine, a hydraulic transmission including a pump driven by said engine and a motor energized by said pump for driving said shaft, means fdr adjusting said mechanical transmission to connect the two parts thereof and thereby render said mechanical transmission effective to drive said shaft, means operated in unison with said adjusting means for rendering said hydraulic/transmission ineffective to drive said shaft when the two parts of said mechanical transmission are connected, and other means for reversing said hydraulic motor.

2. The combination, with a shaft and an engine for driving said shaft, of a mechanicaltransmission having one part thereof connected to said shaft to drive the same and another part'connected to and driven by said engine, a hydraulic transmission including a pump driven by 'sai-d engine and a motor energized by said pump for driving said shaft, means for adjusting said mechanical transmission to connect the two parts thereof and thereby render said mechanical transmission effective to drive said shaft, a valve for bypassing at least a part of the liquid discharged by said pump, and means for operating said valve and said adjusting means simultaneously.

3. The combination, with a shaft and an engine for driving said shaft, of a mechanical transmission having one part thereof connected to and driven by said engine and a second part connected to and rotatable with said shaft and adapted to be connected to said first part to thereby enable said engine to drive said shaft through said transmission, a hydraulic transmission including a pump driven by said engine and a hydraulic motor connected to said shaft and energized by liquid supplied to it by said pump to enable it to drive said shaft, means for varying the displacement of said pump to thereby vary the speeds of said motor and said shaft relative to the speed of said engine, means responsive to a variation in the relative speeds of said shaft and said engine for operating said displacement varying means to thereby cause said motor to drive said shaft at a speed proportional to the speed of said engine, means for adjusting said speed responsive means to regulate the speed of said shaft relative to the speed of said engine and thereby permit the speeds of the two parts of said mechanical transmission to be synchronized, and means for connecting the two parts of said mechanical transmission to each other.

4. The combination, with a shaft and an engine for driving said shaft, of a mechanical transmission having one part thereof connected to and driven by said engine and a second part connected to and rotatable with said shaft and adapted to be connected to said first part to thereby enable said engine to drive said shaft through said transmission, a hydraulic transmission including a pump driven bysaid engine and a hydraulic motor connected to said shaft and energized by liquid supplied to it by said pump to enable it to drive said shaft, means for varying the displacement of said pump to thereby vary the speeds of said motor and said shaft relative to the speed of said engine, means responsive to a variation in the relative speeds of said shaft and said engine for operating said displacement varying means to thereby cause said motor to drive said shaft at a speed proportional to the speed of said engine, means for adjusting said speed responsive means to regulate the speed of said shaft relative to the speed of said engine said mechanical transmission to each other, and

means operable in unison with said connecting means for rendering said hydraulic transmission ineffective to drive said shaft when the two parts of said hydraulic transmission are connected.

5. The combination, with a shaft and an engine for driving said shaft, of a mechanical transmission having one part thereof connected to and driven by said engine and a second part connected to and rotatable with said shaft and adapted to be connected to said first part to thereby enable said engine to'drive said shaft through said transmission, a hydraulic transmission including a pump driven by said engine and a hydraulic motor connected to said shaft and energized by liquid supplied to it by said pump to enable it to drive said shaft, means for varying the displacement of said pump to thereby vary the speeds of said motor and said shaft relative to the speed of said engine, means responsive to a variation in the relative speeds of said shaft and said engine for operating said displacement varying means to thereby cause said motor to drive said shaft at a speed proportional to the speed of said engine, means for adjusting said speed responsive means to regulate the speed of said shaft relative to the speed of said engine and thereby permit the speeds of the two parts of said mechanical transmission to be synchronized, power means for connecting the two parts of said mechanical transmission to each other,

and means operable only when said adjusting means is in a predetermined position for effecting operation of said power eans.

6. The combination, wit a shaft and an engine for driving said shaft, of a mechanicaltransmission having one part thereof connected to and driven by said engine and a second part connected to and rotatable with said shaft and adapted to be connected to said first part to thereby enable said engine to drive said shaft through said transmission, a hydraulic transmission including a pump driven by said engine and a hydraulic motor connected to said shaft and energized by liquid supplied to it by said pump to enable it to drive said shaft, means for varying the displacement of said pump to thereby vary the speeds of said motor and said shaft relative to the speed of said engine, means responsive to a variation in the relative speeds of said shaft and said engine for operating said displacement varying means to thereby cause said motor to drive said shaft at a speed proportional to the speed of said engine, means for adjusting said speed responsive means to regulate the speed of said shaft relative to the speed of said engine and thereby permit the speeds of the two parts of said mechanical transmission to be synchronized, means for connecting the two parts of said mechanical transmission to each other, and means for reversing said motor.

7. The combination, with a shaft and an engine for driving said shaft, of a mechanical transmission having one part thereof connected to and driven by said engine and a second part connected to and rotatable with said shaft and adapted to be connected to said first part to thereby enable said engine to drive said shaft through said transmission, a hydraulic transmission including a pump driven by said engine and a hydraulic motor connected to said shaft and energized by liquid supplied to it by said pump to enable it to drive said shaft, means for varying the displacement of said pump to thereby vary the speeds of said motor and said shaft relative to the speed of said engine, means responsive to a variation in the relative speeds of said shaft and said engine for operating said displacement varying means to thereby cause said motor to drive said shaft at a speed proportional to the speed of said engine, means for adjusting said speed responsive means to regulate the speed of said shaft relative to the speed of said engine and thereby permit the speeds of the two parts of said mechanical transmission to be synchronized, means for adjusting said mechanical transmission to connect and disconnect the two parts thereof, a valve for bypassing atleast a part of the liquid discharged by said pump, and means for operating said adjusting means and said bypass valve simultaneously.

8. The combination, with a shaft and an engine for driving said shaft, of a mechanical trans mission having one part thereof connected to and driven by said engine and a second part connected to and rotatable with said shaft and adapted to be connected to said first part to thereby enable said engine to drive said shaft through said transmission, a hydraulic transmission including a pump driven by said engine and a hydraulic motor connected to said shaft and energized by liquid supplied to it by said pump to enable it to drive said shaft, means for varying the displacement of said pump to thereby vary the speeds of said motor and said shaft relative to the speed of said engine, a three legged differential having one leg rotated by said engine and a second leg rotated by said shaft whereby the third ld'gwill rotate in response to a variation in the relative speeds of said engine and said shaft, a hydraulic servo-motor for operating said displacement varying means, means for supplying liquid to said servo-motor including a pilot valve for controlling the delivery of liquid thereto and operated in response to rotation of the third leg of said differential, a follow-up mechanism for transmitting motion from said displacement varying means to said pilot valve, and means for simultaneously rendering one transmission effective and the other transmission ineffective to drive said shaft.

9. The combination, with a shaft and an en gine for driving said shaft, of a mechanical transmission having one part thereof connected to and driven by said engine and a second part connected to and rotatable with said shaft and adapted to be connected to said first part to thereby enable said engine to drive said shaft through said transmission, a hydraulic transmission including a pump driven by saidengine and a hydraulic motor connected to said shaft and energized by liquid supplied to it by said pump to enable it to drive said shaft, means for varying the displacement of said pump to thereby vary the speeds of said motor and said shaft relative to the speed of said engine, a three legged differential having one leg rotated by said engine and a second leg rotated by said shaft whereby the third leg will rotate in response to a variation in the relative speeds of said engine and said shaft, a hydraulic servo-motor for operating said displacement varying means, means for supplying liquid to said servo-motor including a pilot valve for controlling the delivery of liquid there to and operated in response to rotation of the third leg of said diiferential, a follow-up mechanism for transmitting motion from said displacement varying means to said pilot valve, means for adjusting said mechanical transmission to connect and disconnect the two parts thereof, a valve for bypassing at least a part of the liquid discharged by said pump, and means for operating said adjusting means and said bypass valve simultaneously.

10. The combination, with a first shaft, a second shaft and an engine connected to said first shaft to drive the same, of a variable speed mechanical transmission connected to said shafts and including a plurality of gear trains selectively engageable to enable said transmission to drive said second shaft from said first shaft at any one of a plurality of definite speed ratios and disengageable to render said transmission ineffective to drive said second shaft, means for adjusting said transmission to engage or disengage said gear trains, a hydrauligtransmission for driving said second shaft from said first shaft including means for adjusting it to vary the speed ratios of said shafts through a stepless range, a control transmission including a ratio adjuster driven from one of said shafts and a three legged differential having one leg driven from that shaft through said adjuster and a second leg driven from the other shaft whereby its third leg will rotate in response to adjustment of said adjuster or to a variation in the relative speeds of said shafts, means for operating said hydraulic transmission adjusting means in response torotation of the third leg of said differential to thereby correct a variation in the 75 speed of said second shaft or to vary the speed of said second shaft in response to adjustment of said ratio adjuster, means for adjusting said ratio adjuster to thereby vary the speed of said second shaft relative to the speed of said first shaft, and means responsive to engagement of said gear trains for rendering said hydraulic transmission ineffective to drive said second shaft and responsive to disengagement of said gear trains for rendering said hydraulic transmission efiective to drive said second shaft.

11. The combination, with a first shaft, a second shaft and an engine connected to said first shaft to drive the same, of a variable speed mechanical transmission connected to said shafts and including a plurality of gear trains selectively engageable to enable said transmission to drive said second shaft from said first shaft at any one of a plurality of definite speed ratios and disengageable to render said transmission ineffective to drive said second shaft, means for adjusting said transmission to engage or disengage said gear trains, a hydraulic transmission for driving said second shaft from said first shaft including means for adjusting it to vary the speed ratios of said shafts through a stepless range, a control transmission including a ratio adjuster driven from one of said shafts and a three legged differential having one leg driven from that shaft through said adjuster and a sec-ond leg driven from the other shaft whereby its third leg will rotate in response to-adjustment of said adjuster or to a variation in the relative speeds of said shafts, means for operating said hydraulic transmission adjusting means in response to rotation of the third leg of said differential to thereby correct a variation in the speed of said second shaft or to vary the speed of said second shaft in response to adjustment of said ratio adjuster, means for adjusting said ratio adjuster to thereby vary the speed of said second shaft relative to the speed of said first shaft, means for locating said ratio adjuster adjusting means in a position in which the ratio of said control transmission is such that said hydraulic transmission is caused to drive said second shaft at such a speed that the speed ratio of said shafts is identical to a speed ratio of said mechanical transmission, and power means operable only when said adjuster adjusting means is in said position for operating said mechanical transmission adjusting means.

12. The combination, with a first shaft, a second shaft and an engine connected to said first shaft to drive the same, of a variable speed mechanical transmission connected to said shafts and including a plurality of gear trains selectively engageable to enable said transmission to drive said second shaft from said first shaft at any one of a plurality of definite speed ratios and disengageable to render said transmission ineffective to drive said sec nd shaft, means for adjusting said transmission to engage or disengage said gear trains, a hydraulic transmission for driving said second shaft from said first shaft including means for adjusting it to vary the speed ratios of said shafts through a j tepless range, a control transmission including a-ratio adjuster driven from one of said shafts and a three legged differential having one leg driven from that shaft through said adjuster and a second leg driven from the other shaft whereby its third leg will rotate in response to adjustment of said adjuster or to a variation in the relative speeds of said shafts, means for operating said hydraulic transmission adjusting means in response to rotation of the third leg of said differential to thereby correct a variation in the speed of said second shaft or to vary the speed of said second shaft in response to adjustment of said ratio adjuster, means for adjusting said ratio adjuster to thereby vary the speed of said second shaft relative to the speed of said first shaft, means for locating said ratio adjuster adjusting means in a position in which the ratio of said control transmission is such that said hydraulic transmission is caused to drive said second shaft at such a speed that the speed ratio of said shafts is identical to a speed ratio of said mechanical transmission, power means operable only when said adjuster adjusting means is in said position for operating said mechanical transmission adjusting means, and means responsive to engagement of said gear trains for rendering said hydraulic transmission inefiective to drive said second shaft and responsive to disengagement of said gear trains for rendiring said hydraulic transmission eifective to drive said second shaft. 10

WALTER FERRIS. 

